Well there is the biblical reference.
But it is also a military term, in particular Rome had so many legions.
And I suppose there are the assorted legions you can now go to, to play pool/darts etc for veterans.

As far as the spelling goes, its a pretty basic word.
If someone has an issue getting to www.legion.com (or .org etc), they're probably not going to be boxing much, as I would imagine simple macro's will be beyond them too.